Gas turbine engines in an aircraft may obtain additional thrust by the use of augmentors or afterburners. Fuel is injected into the gas stream at a location downstream of the turbine. The fuel is ignited and burned prior to gas exhaust through the nozzle.
In this high velocity airstream it is difficult to maintain a stable flame front. For this purpose flameholders are used. They conventionally are in the form of V or U-shaped gutters with the opening facing downstream. This produces a local turbulence retaining the flame front at the gutter. These gutters will often comprise an annular gutter plus some radial gutters extending outwardly therefrom.
The fuel injection may be staged through different injection points. One of these stages, usually the first one, is located just upstream of an annular gutter. A spray ring is used to introduce the fuel at this location. Shrouds are used to confine the air and fuel in the gutters' area.
The spray ring will generally introduce the fuel transverse to the gas flow at the location just upstream of the gutter. This provides a dynamic interaction between the high velocity airflow and the fuel promoting atomization and mixing.
Cracking has occurred where the shroud supports are connected to the shrouds. This apparently has resulted from low cycle fatigue damage caused by temperature differences during certain operations.